The founder and owner of fast-food chain Supermac's says he is concerned we could see a food shortage this winter.
Pat McDonagh says the price of key products has increased sharply, and the cost of producing food could result in less food being produced.
He was speaking as rival chain McDonald's increased its Irish prices on some items.
Many of its core offerings will go up in price, with a cheeseburger costing €1.70 - up from €1.50.
In a statement McDonald's says it is feeling the impact of rising inflation, and is seeing the cost of everyday items - such as food and energy - increase.
Mr McDonagh told The Hard Shoulder the invasion of Ukraine is having a huge impact.
"Everybody has to get through it, we have to adapt to the new situation and deal with it - and it will level itself out.
"I would be concerned, though, in one sense there could be a little bit of a scarcity of food towards the end of the winter up towards December.
"The way things are with the war in Ukraine, etc it has a massive knock-on effect right across the whole world really".
He believes food productivity here will fall back.
"I would be recommending people to buy a bit of long-life food earlier on.
"The price of, say, cooking oil has nearly doubled in the last six months because most of it comes from the sunflower in Ukraine.
"That's not being produced in a lot of cases this year... and then the cost of fertiliser, farmers didn't fertilise this year.
"So I think you'll have a lowering of the food productivity in this country as well for the autumn.
"I can't predict what happens, but I'm just assessing it in my own way".